Furnace construction



S. WALLIS ET AL FURNACE CONSTRUCTION- Oct. 26, 1943.

Filed NOV. 2, 1942 JOA ATTORNEY.

change tubes.

Patented Oct. 26, 1943 mm s'rss FATE FURNACE CONSTRUCTION and John W. Throckmcr- John S. Wallis, Darien, Conm, assignors to Petra-Chem Company, New York, N. Y., a corporation of Delaware ton, Wilton, Development Application November 2. 1942, Serial No. 464,210 4 Claims. (Cl. 122-510) Our invention relates to improvements in tubular furnace construction.

The invention particularly resides in vertical tubular furnaces of the type used for heating fluids in distillation or cracking operations of hydrocarbon oils, in the heating of fluids in chemical processes or the generation of steam.

Furnacesof this type have a combustion chamber which encloses a bank of vertical heat ex- These tubes provide a continuous passage through the combustion chamber for fluid to be heated. Heating gases are supplied periodically cleaned and inspected, and repaired or replaced.

Two methods of positioning the tubes in. the furnace have been employed, suspension of the tubes by their upper ends from the top of the combustion chamber, and supporting the tubes by their lower extremities on the bottom of the combustion chamber. If the tubes are suspended from their upper ends, it is necessary to reinforce the furnace to take care of the added weight. This expense and added weight is obviated if the tubes are supported at their lower ends. When supported at the bottom as in the De Florez Patent 1,989,612, dated January 29, 1935, it has been conventional practice to support the weight of the tubes on the lower tube sheet. This sheet is subjected to the heat of the furnace and must therefore have suf icient strength at the high temperatures existing to maintain the entire weight of the tube bank and its accessories. Dimculties are also experienced in inspection of the lower tube sheet and supports when the furnace is in operation.

We have devised a novel supporting structure for the tubes by which the weight of the tubes is carried by the lower supporting structure of the furnace, instead of the highly heated tube sheet. Furthermore, the supports upon which the tubes rest are located outside of the heating zone and are easily inspected since they are readiiy available and unaffected by the furnace heat.

An important object of our invention is the provision of a novel supporting structure for the tubes of a tubular furnace by means of which the weight of the tubes is carried by the lower portion of the furnace supporting structure which positions the supports out of the heating zone.

Other objects and advantages of our invention will be apparent during the course of the following description.

In the drawing, forming a part of this specification and wherein like numerals are employed to designate like parts throughout the same,

Fig. 1 is a fragmentary lower portion of a tubular furnace showing my improved supporting structure for the tubes,

Fig. 2 is a transverse sectional view taken on the line 2-2 of Fig. l,

Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 2, and

Fig. 4 is a transverse sectional view taken on the line 4-6 of Fig. l.

The furnace is carried upon supports Ill. The fragmentary portion of the furnace shown in the drawing includes a cylindrical outer casing l l lined with refractory i2, and a lower metallic tube sheet is protected with refractory it.

Vertical heat exchange tubes are disposed in a circle about the combustion chamber C and adjacent the wall of refractory M. The tubes extend through refractory i i and tube sheet 53 into an annular housing 553. The lower ends of tubes E5 are connected by return bend headers it. As shown in Fig. 3, each header supports two of the tubes. A plug 68 below each of the tubes is is removable for purposes of cleaning and inspection. Lugs is on the headers ii rest upon brackets 2E5 projecting from the walls of housing it. Hinged doors tea. in'the bottom of housing it, below headers El, permit ready access to the headers for removal of plugs to and inspection of the tube supporting means as and 253.

By providing the supporting means on the headers H, the tube supporting structure, including both the lugs on the tubes and brackets on the furnace supports, are located out of the heating zone. Also, the doors lSa provide easy access to the supporting structure.

A further advantage of locating the supporting means on the header is the elimination of machining or welding the exterior surface of the tubes themselves. Where a tube has been machined or welded, the tube abutting is weakened and is more likely to rupture or to be distorted by heat and excessive stress imposed thereon for any cause. By attaching or amxing the supporting means to the header, these difliculties are eliminated.

NT orvics It may thus be seen that we have accom-- plished the objects of our invention. We have provided a supporting structure for the vertical tubes l5 by means of which the weight of the tubes is carried by the lower supporting structure of the furnace. The tube supporting structure is positioned out of the heating zone and where it can be easily inspected at all times.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example and that various changes in the size, shape, and arrangement of parts may be resorted to without departing from the spirit of our invention or the scope of the appended claims.

Having thus described our invention, we claim:

1. Supports for vertical heat exchange tubes whose extremities extend outside the heating chamber of a furnace structure and are connected by return bend headers, including support members on the headers and brackets mounted on the furnace supporting structure, said support members and brackets located outside the heating chamber and coacting to support the weight of the tube bank.

2. Supports for vertical heat exchange tubes whose extremities extend outside the heating chamber of a furnace structure and are con nected by return bend headers, including support members on the headers and brackets mounted on the furnace supporting structure, said support members and brackets located outside the heating chamber and coacting to support the chamber of a furnace structure and are connected by 'retum bend headers, members on the headers and including support brackets mounted on the furnace supporting structure, 'said support members and brackets located outside the heating chamber and coacting .to support the weight of the tube bank, and a housing insulated from the heating chamber enclosing the extending ends of the tubes and their supports, said housing having openings permitting ready access to the headers and supports.

4. Supports for vertical heat exchange tubes whose extremities extend outside the heating chamber of a furnace structure and are connected by return bend headers, including support members on the headers and brackets mounted on the furnace supporting structure, said support members and brackets located outside the heating chamber and coacting to support the weight of the tube bank, a housing insulated from the heating chamber enclosing the extending ends of the tubes and their supports, said housing having openings permitting ready access to the headers and supports, and cover plates for the housing openings.

' JOHN S. WALLIS.

JOHN W. THROCKMORTON. 

